As someone that has a Wii U and plays games mostly (99%) on the bigscreen....I feel like I already own the non-slim version of this system. I feel like the Switch is actually the Wii U S or Wii U Slim.
So not terribly excited. They showed off Mario, MarioKart, Splatoon and Zelda that can either be played on the Wii U or look like they would have no trouble running on the Wii U.
The Switch looks much more appealing as a successor to the 3ds. It's like if the 3ds was more like this at launch then I would never have bought a Wii U.
It's also appealing if this is indeed Nintendo's 1 platform to rule all them all and you won't have to get your panties in a bunch because a new mario or zelda game is on the handheld and not on the big screen system. That will be huge and likely get me to buy the system anyway.
And if you can still play wireless local multiplayer when docked then I might buy two or three.